1. Field of the Invention
This invention relates to a fluid cleaning system and more particularly to a permanent electrically charged shaped fiber filtration media.
2. Description of Prior Art
It is known to produce electrically charged filters. However, present electrically charged filtration media are very expensive and prone to lose their charge depending upon the environment in which they are used. The electrically charged media better known as electret media is very expensive and the charge can be permanently lost. Triboelectric media has been prepared in a number of ways including 1)woven glass fabrics which are coated with a PTFE powder dispersion, 2) filters consisting of a series of polyester media and nylon media in series behind each other, and 3) melt processed CTFE and PTFE fibers.
Triboelectrification is the process by which two specific materials in surface contact can accumulate opposite electrical charges on their surfaces. The phenomenon originates in the transfer of electrons close to the surface from one material to the other. In order for triboelectrification to occur it is not essential for one surface to cause friction on the other surface. By trying out different pairs of materials, triboelectric series have been established which lists materials starting with those which most easily accept a positive electrical charge and ending with materials which most easily accept a negative electrical charge. In theory the triboelectrification effect achievable is dependent on the dielectric constant of the materials used. R. P. Lehman in an 1988 article entitled "Optimized Powder Coating of Critical Objects", provides an exemplary list of such materials, in descending order of their relative dielectric constants from the positive end to the negative end. To achieve maximum chargeability it is believed the two materials should differ considerable in their dielectric constants.